The invention relates generally to machines for grinding and reforming the surfaces of railroad track rails. More particularly, the invention relates to an apparatus and method for directing a spark stream generated by contact between a rotating grinding stone and a railhead away from combustible materials in the vicinity of the grinding operation.
Railroad track rails are subject to wear by the passage of trains over the rails, and the head surfaces of railroad track rails which are in direct contact with the wheels and wheel flanges of rolling stock tend to wear unevenly. In particular, the cross sectional contour of the head can become misshapen, and depressions in the top surface of the railhead may develop such that the railhead presents a modulating, corrugated surface. Moreover, the railhead may develop burrs or otherwise lose its symmetrical profile. Such defects create undesirable vibration, particularly at high speeds, and also produce high noise levels. Maintenance of smooth running surfaces on railroad track rails is therefore important for reasons of safety, riding comfort, protection of the track, track bed and rolling stock, noise suppression.
Grinding machines have been developed for maintaining railroad track rails in smooth, properly shaped condition. Such grinding machines generally comprise a plurality of rotatable grinding modules carried by a locomotive or the like in close proximity to the railhead surfaces of the track rail. The grinding modules include rotatable, abrasive grinding stones that can be lowered into a position flush with the rail surface to grind and restore the rail surface to a smooth, desired profile. In particular, on-track grinding trains carrying arrays of heavy grinding stones powered by high horsepower motors have been used in such grinding operations. An example of such a rail grinding car is disclosed in U.S. Pat. No. 4,583,327, in which there is described a rail grinding car having vertical and horizontal grinding stone units. Horizontal grinding stones are generally annular with a flat, annular face being the grinding surface, whereas vertical grinding stones grind with an outer cylindrical surface of the stone. This grinding car embodies positioning control of an array of vertical grinding stones so that each stone properly engages the rail, and wherein the horizontal grinding stones are individually positionable to provide flexibility in grinding location and concentration on the rail heads.
A well known problem with rail grinding machines is the generation of sparks and swarf, which is an intimate mixture of metal and/or stone grinding chips and fine abrasive dust generated by the grinding operation. Sparks can be particularly troubling because of the potential to start fires. Sparks directed to the outside, i.e., “field” side, of the rails can set fire to brush and dried vegetation along the tracks. Additionally, sparks directed toward the “gauge” side, i.e., inside, of the rails, can set fire to the railroad ties. The sparks can also present a safety hazard to personnel involved in the grinding operation. Often, the mere threat of a fire hazard in extremely dry areas may require the cessation of grinding activities, prolonging the time to accomplish necessary track maintenance and increasing maintenance costs.
A number of designs have been proposed to contain, suppress, or evacuate the sparks and swarf by-products of rail grinding. For example, some grinding machines have been fitted with metal flaps on the field sides of the machines in proximity to the grinding stones. Such flaps are effective in containing some of the byproducts by presenting a physical barrier. The aforesaid U.S. Pat. No. 4,583,327 discloses a rail grinding machine wherein the grinding stones are surrounded by shrouds, and a source of negative pressure cooperates within the shrouds to pull dust and sparks away from the grinding area. U.S. Pat. No. 5,111,624, assigned to Loram Maintenance of Way, Inc., discloses a grinding machine for limiting the dispersion of sparks and swarf wherein a fan is carried by the grinding head assembly, above the grinding stone, of a railroad track rail grinding unit. The fan rotates with the grinding stone during grinding operations and creates a downward draft of air to limit the dispersion of sparks and swarf. Water and/or a surfactant can also be introduced into the downdraft. The '624 patent assigned to Loram Maintenance of Way, Inc., also refers to a grinding machine wherein water is sprayed by specially designed and positioned nozzles in the vicinity of the grinding area.
However, the efforts described above can be less effective than desired for controlling the potential for sparks emanating from the grinding operations to cause fires, either by igniting brush on the field side of the rails, or the railroad ties on the gauge side thereof. All of the devices described above are directed toward containing the sparks (and swarf), or limiting the dispersion thereof. Moreover, these efforts have not been very successful, as sparks from rail grinding operations continue to be a significant problem in rail grinding operations.
Accordingly, there is a need for an apparatus and method for reducing the likelihood that sparks generated by rail grinding operations will cause a fire.